Meiosis consists of two cycles; Meiosis I and Meiosis II. They both include prophase, metaphase, anaphase, and telophase. The two cycles differ in that they include roman numerals to represent which cycle they fall under. In interphase, the chromosomes are replicated, and then move onto prophase I the nuclear envelope disappears. Additionally, parent cells have homologous chromosomes, one from the father and one from the mother and can be mixed many different ways ensuring genetic variation. In prophase I, crossing over occurs which is when chromosomes exchange genes and results in non identical chromatids. Genes A and a can switch with genes but they cannot switch with genes B and b. In metaphase I, the sister chromatids (tetrads) line up …show more content…
It is a disorder that causes tumors to grow on nerve tissue due to a distribution of cell growth in the nervous system. The tumor can grow anywhere in the nervous system such as the spinal cord, nerves, and the brain. This disorder is commonly diagnosed in early adulthood or childhood. Usually a person inherits the gene from one of their parents. The child only needs one copy of the mutated gene in order to get the disorder. A child has a 1 in 2 chance of getting neurofibromatosis if the parent has NF1. The mutation is not 100% as it where it occurs because it is relatively new, but most likely happened in the child’s parent’s production of either the egg or sperm. Neurofibromatosis is caused by a mutation on chromosome 17. The protein, neurofibromin, regulates the activity of the protein, ras, which initiates cell division. When the gene (NF1) is mutated, the neurofibomin protein can’t attach to ras, meaning no activity regulation. The result of this mutation causes the ras protein to become more active. This tells the cells to start dividing and never tells them when to stop, therefore creating tumors. The major phenotypic characteristic of individuals that are distinct to neurofibromatosis are café au lait spots, which are the color of coffee with milk, and freckles. The spots and freckles will increase over time, with age. Some other physical characteristics that may appear with disorder is the curvature of the spine, scoliosis, bone defects, learning disabilities, and optic